From the onset of Russia’s full-scale invasion of Ukraine on February 24, 2022, the specter of nuclear weapons has loomed ominously. In his speech announcing the invasion, Vladimir Putin falsely accused Ukraine of aspiring to acquire nuclear weapons, citing this as a justification for war. Russian media amplified these claims, alleging that Ukraine was developing “dirty bombs” — devices combining conventional explosives with radioactive material intended to spread contamination without a nuclear explosion.
This nuclear saber-rattling isn’t just propaganda; it’s been a strategic military tool for Russia. While it hasn’t dampened Ukrainians’ resolve to defend their country, it has succeeded in delaying Western military aid. This hesitation has made the war more costly for Ukraine, both in lives and resources, and is also directly responsible for the current dangerous situation at the front. But to fully grasp Russia’s nuclear strategy, we need to revisit the history of Ukraine’s nuclear disarmament.
Thirty years ago, under the Budapest Memorandum, Ukraine surrendered the world’s third-largest nuclear arsenal, inherited after the Soviet Union’s collapse. In exchange, Russia, the United States, and the United Kingdom provided “security assurances” to respect Ukraine’s sovereignty and borders.
Yet, when Russia annexed Crimea in 2014 and again when it launched its full-scale invasion in 2022, these assurances proved hollow. Days before the full scale invasion, Ukrainian President Volodymyr Zelensky invoked the Budapest Memorandum, seeking consultations with the guarantors. The Russian army heading toward Kyiv was the response.
Surprisingly, the Budapest Memorandum is rarely mentioned in Western discussions about aid to Ukraine. Many in the United States are unaware of it, even among policymakers. When I asked a congressional aide why the treaty isn’t cited more often, he responded, “That’s a good question.”
In Ukraine, the memorandum has become synonymous with betrayal. However, it is important to understand that Ukraine’s decision to disarm was influenced by multiple factors: the traumatic legacy of the 1986 Chernobyl disaster, a desire for integration into the international community, the need of Western financial assistance, and intense political pressure from both Russia and the United States.
Zelensky’s recent “NATO or nukes” remark epitomizes the complete loss of faith among Ukrainians in the nuclear non-proliferation regime. Western countries, shielded by the NATO nuclear umbrella, are only now beginning to grasp this reality.
Steven Pifer, a former U.S. negotiator of the Budapest Memorandum, warned in 2022 that “non-proliferation efforts may turn out to be another important casualty of the war.” Indeed, the New START Treaty, the only remaining nuclear arms control agreement between the United States and Russia, is set to expire in February 2026, paving the way for a potential new era of an unrestricted nuclear arms race. This threat is compounded by the rapid expansion of China’s nuclear arsenal and Washington’s plan to modernize its nuclear weapons. Today’s generation faces the daunting challenge of a world once again shadowed by the specter of nuclear weapons.
In the shadow of a nuclear bomb
Will Putin use nukes? Experts believe it’s unlikely, but they also acknowledge that no one—not even Putin—truly knows.
A 2020 study on Russian escalation management concluded that, in a regional war—a smaller-scale version of a potential Russia-NATO conflict—the Russian military may resort to tactical nuclear weapons either on the battlefield or as an intimidating demonstration.
However, despite aggressive rhetoric, there’s no concrete evidence that Russia is preparing for such an escalation in Ukraine.
Professor of strategic studies Phillips O’Brien points out that according to academic models and war games, Russia should have already resorted to nuclear weapons. Yet, it hasn’t — likely due to pressure from countries like China and India. The prolonged conflict because of the West’s undersupply of military aid to Ukraine increases the risk. A drawn-out, bloody war heightens tensions and could push Putin toward desperate measures. This argument runs counter to the Western strategy of appeasing Putin by limiting support to Ukraine, as the “boiling-the-frog” war strategy may be even riskier. Furthermore, drawing on historical lessons from the bombings of Hiroshima and Nagasaki, Mariana Budjeryn suggests that even if Russia were winning, it might still use nuclear bombs to shape Europe’s post-war dynamics.
I would like to emphasize that the likelihood of using non-strategic nuclear weapons is definitely not zero. Judging by past behavior (e.g., Russia’s unilateral suspension of the Treaty on Conventional Armed Forces in Europe was followed by the 2008 invasion of Georgia, and the official recognition of separatist “republics” prior to the full-scale invasion of Ukraine), Putin operates with a legalist approach. Therefore, the amendments to Russia’s nuclear doctrine and the de-ratification of the Comprehensive Nuclear-Test-Ban Treaty indicate a nonzero probability of nuclear use.
Zaporizhzhia Nuclear Power Plant as a nuclear noose
Perhaps the most immediate nuclear threat isn’t a bomb but the dire situation at the Zaporizhzhia Nuclear Power Plant (ZNPP), Europe’s largest nuclear facility. Occupied by Russian forces since the start of the full-scale invasion, the ZNPP has posed far more serious leverage over Ukraine than Putin’s nuclear threats. Russian military personnel have been stationed on-site at ZNPP, along with tanks, armored personnel carriers, and utility trucks. Russian forces have placed anti-personnel mines both inside and outside the plant. The ZNPP has effectively been converted into a military base, housing equipment and training artillery units that shell Nikopol without fear of Ukrainian retaliation.
The presence of military equipment and personnel not only increases risks to the plant’s safety systems but also restricts access to the facility, hindering nuclear engineers from performing their duties. Additionally, this situation creates a highly stressful environment for the plant’s staff, further jeopardizing operational safety.
History has shown that the safety of nuclear power plants heavily depends on their operators. Since the occupation began, Ukrainian engineers have been working under constant threats from the occupying forces, and the living conditions in Energodar, the city adjacent to ZNPP where workers live, have significantly deteriorated. Workers at ZNPP have been subjected to forced labor by Russian forces, with widespread reports of torture. Andriy Honcharuk, a diver at ZNPP, was tortured to death after he refused to assist the occupiers in their efforts to drain water from the cooling system and stop the pumps essential for reactor safety. Even when not generating electricity, nuclear plants require constant cooling to prevent a reactor meltdown — a grave accident similar to the 2011 Fukushima disaster. Honcharuk’s heroic sacrifice was recognized by President Zelensky posthumously awarding him the Order of Courage.
To maintain the cooling of the station, an uninterrupted supply of water and electricity is absolutely essential. The electricity supply has been interrupted multiple times due to damage to power lines from military activity. In such instances, the station relies on backup diesel generators. Should these generators fail, a meltdown would likely occur.
Since ZNPP draws cooling water from the Kakhovka reservoir, the water supply was jeopardized after Russia’s destruction of the Kakhovka dam. However, Ukraine’s Ministry of Energy reports that water levels in the cooling pond at ZNPP remain stable.
Another matter of concern is understaffing. Before the start of the war, there were 12,000 workers at ZNPP and in Enerhodar city, but 80% of Ukrainian workers have managed to evacuate. Currently, only 5,000 employees work at the plant. Recognizing the staffing problem, the occupying authorities plan to expand the workforce to 6,000, though the quality of these new recruits is concerning. I am aware of ten Ukrainian nuclear engineers who have been abducted by the occupying forces, with their whereabouts currently unknown. The remaining Ukrainian staff — upon whom the safety of the entire plant depends — are effectively being held hostage by the Russians and are being forced to adopt Russian citizenship to continue working at the plant and to access basic social services and healthcare.
The Union of Concerned Scientists has warned of catastrophic consequences if the plant is attacked. They also note that keeping reactors in shutdown modes with fuel in the core, as at Zaporizhzhia, is rare and raises risks due to untested conditions. A fire broke out at ZNPP less than a week after Ukraine’s incursion into the Kursk region, following multiple blasts that damaged the plant’s cooling systems. The International Atomic Energy Agency (IAEA) Chief Rafael Grossi warned, “These reckless attacks endanger nuclear safety at the plant and increase the risk of a nuclear accident. They must stop now.” Grossi didn’t attribute blame. IAEA reports daily military activity in the vicinity and some explosions occurring close to the plant.
It is worth noting that the IAEA is not a neutral party — its Deputy Director General, Mikhail Chudakov, is a former manager at Russia’s Rosenergoatom nuclear utility, which raises concerns about potential conflicts of interest. In March 2022, Greenpeace East Asia called on the IAEA to suspend Chudakov’s appointment to preserve the organization’s credibility, as his appointment likely required Putin’s support. Greenpeace Germany has also condemned the IAEA for failing to identify Russia as the real cause of safety risks at ZNPP.
In the annals of nuclear history, ZNPP will stand as yet another example demonstrating why nuclear energy cannot be considered safe. This contrasts with the IAEA’s enthusiastic promotion of nuclear energy as a solution for climate change, despite abundant evidence that it is neither economically viable nor scalable, not to mention the significant safety concerns (to be fair, the IAEA is not alone in this effort). Just as international organizations, including the IAEA, downplayed the consequences of Chernobyl — the worst nuclear catastrophe — the IAEA is downplaying the situation at ZNPP.
What is to be done?
Russia’s actions at ZNPP, provocations at another Ukrainian nuclear plant, the 2022 occupation of the Chernobyl power plant as an integral part of its failed blitzkrieg, along with its nuclear rhetoric and withdrawal from key arms treaties, are part of a broader strategy aptly named “hybrid nuclear war” by Georgiy Balakan at the beginning of the full scale invasion. Russia’s hybrid nuclear war on Ukraine facilitates its openly genocidal war with conventional weapons. Just as the preceding conventional hybrid wars in Moldova, Georgia, and pre-2022 Ukraine, the nuclear hybrid war is making the world less safe.
What is to be done? The most effective solution is a Ukrainian victory, which could pave the way for a democratic transformation in Russia and lasting peace in Europe. In the short term, sustained military and humanitarian aid to Ukraine is essential.
Since the global nuclear arsenal has started increasing for the first time since 1985, we must draw inspiration from the mass mobilizations of past generations, whose efforts led to landmark arms control agreements. For example, if you are like me — a physicist (even if you are just an undergraduate student) — consider joining the Physicists Coalition for Nuclear Threat Reduction.
Another immediate step is supporting efforts to neutralize the nuclear threat at ZNPP. Celebrated Ukrainian progressive intellectual and soldier Taras Bilous has proposed that the United Nations General Assembly establish a demilitarized zone around the plant, similar to measures taken during the Suez Crisis in 1956. A petition supporting this initiative needs to be supported and distributed. While international institutions are currently ineffective — as highlighted by the ongoing catastrophic Israel-Gaza war — a call from the international community can still make a difference. This is especially important in light of the coming Trump administration, which may push for a Ukraine ceasefire. A U.N. resolution to demilitarize ZNPP would not only be a significant step toward reducing nuclear risks in the region, but also a significant victory for people’s diplomacy.
